Spray gun air valve



May l0, 1955 R. B.'M|rcHE|.L

SPRAY GUN AIR VALVE Filed Jan. 25, 1951 ELEM/TE.

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Cttorneg TEA United States Patent SPRAY GUN Am VALVE Robert BertramMitchell, Sanderstead, England, assigner to The De Vilbss Company,Toledo, Shin, a corporation of Ohio Application `l'alruary 25, 1951,Serial No. 207,724

1 Claim. (Cl. 251-229) This invention relates to spray guns utilizingcompressed air for atomizing the spray material and having diametricallyopposed air jets for attening the atomized material stream into fanshape. In order to secure spray patterns of various widths adaptable foreffectively coating surfaces of different areas, it is customary to havean adjustable valve in the passage delivering air for such jets. Theflattening force of the air jets is reduced or increased by closing oropening movement of the valve.

As usually constructed this valve has a tapered inner end which seatswithin the air passage, a threaded shank by which it is rotatablymounted, and an exterior knurled head for manual adjustment. In order toprovide a broad range of adjustment a relatively fine thread isutilized. It Vis thus possible to set the valve for a very particularflow of air that will shape the spray pattern most suitably for acertain type of surface.

In many spray tinishing operations the character of the products beingcoated is such that a single width of spray is satisfactory for allpurposes. However, in other finishing processes, there are occasionalsurfaces of restricted area, for which a Wide spray pattern, selectedfor a major part of the coating work, is not suitable.

Since excessive waste from overspray or too heavy a coating results fromthe use of too wide a spray pattern, under such circumstances it isdesirable for the operator to temporarily screw the spray width valve atleast part way toward a closed position. He must subsequently carefullyopen it again to the predetermined setting considered best for thepredominant type of surfaces. Because of the line thread on the valveshank, considerable rotary movement is required in this closing andopening of the valve and valuable time is lost in the accompanyinginterruption of the spraying operation.

The purpose of my invention is the provision of a valve structure forcontrolling the air delivered to flattening Y jets in a spray gun inwhich the advantage of close adjustment is retained and which inaddition has means for easy and rapid closing and opening movement ofthe valve with stop means limiting the opening movement to the valveposition previously selected for normal use.

This improved action is secured by mounting the valve for both gradualthreaded adjustment and independent sliding axial movement. This isaccomplished by having an unthreaded valve shank fitting snugly forrelative axial movementl within an exteriorly.threadedirtatable' sleeveandprovfidingbetween the valv'eslr'ankf andt'sle'eve a longitudinal slotand pin connection. y

An` embodiment of my invention is hereafter described in detail andillustrated in the accom'panyinfg` drawings in which- Figure 1 is acentral vertical longitudinal section of a spray gun incorporating theinvention;

Figure 2 is a similar section of the valve assembly of the spray gun ofFigure l; in this view the valve is in closed position; y

Figure 3v is a side elevationpartlyin: section-'tof 4vtlrefvalveassembly withA the valve in open position; 'and Figure 4 is a sideelevation of the valve and the exteriorly threaded sleeve.

The spray gun of Figure l is a conventional design to which my inventionhas been adapted. It has a depending handle 1 in which there is an airsupply passage 2. 'The air travels therethrough past valve 3, which isopened by rearward movement of the trigger 4 against the exteriorlyextending valve spindle 5. The air flow continues upwardly through port6 into the horizontal bore 7. The air is here divided into two parts,one travelling forwardly exteriorly of the hollow rod 8. This air passesthrough opening 9 into annular chamber 10, forwardly around the spraymaterial tip and out the annular port surrounding the outlet end of thetip. This portion of the air atomizes the spray material discharged fromthe tip.

The second part of the air reaching bore 7 normally enters the lateralports 12 into the interior of hollow rod S. Under control of valve 13this air travels forwardly out the open end of rod 3 into annularchamber 14 from whence it passes ahead to the outlets in horns 15. Thisair projected against opposite sides of the atomized material streamattens it into fan shape.

The hollow rod 8, in addition to providing a passage for the air goingto the horns, serves to retain the spray head 16 in assembled relationwith the spray gun body 17. lt does this by having a forwardly facingshoulder abutting against the edge of the rearward opening of bore 7 anda threaded forward end engaging the sprayhead. This double function ofrod 8 is a feature of the particular spray gun utilized to illustrate anembodiment of this invention and is incidental to the invention. Thelatter may be as easily applied to spray guns not having this feature.

The interior of the rod t3 is divided into two parts by the annular ange1S forming a valve seat 19 for the valve 13. A sleeve Z0 is threadedinto the rear end of the rod t5, the joint between them being sealed bypacking 21 held in place by nut 22. To resist accidental turning of thesleeve 20 its forward end is slotted at 23 and the sections between theslots are sprung outwardly against the inner wall of rod 8. The valve 13extends neatly through sleeve 20 and the exterior joint therebetween issealed by packing 24 held in piace by nut 2S. For manual adjustment ofvalve 13 there is mounted on the exterior end of the valve shank aknurled knob 26.

Midway of the sleeve 2da. longitudinal slot 27 is cut therethrough. Intothiszsloty snugly ts the head of a screw 2S `from thesideofztheffvalveshank. Through this slot andscrew en'gageraeaf yrtitevalve may be movedlongitudinall'yin relationit' tha-,sleeve within the limits of thelength of the slot. Wi -arotary movement the valve and sleeve must turntogethen,

In normal usageithe. valve 13 is in open position rearwardly spaced fromthe valve seat 19 with the head of the screw 28 against the rear end ofslot 27. Shouldk some adjustment in the position of the valve be desiredthe knurled knob 25 is turned. Through the engageme t of the screw 23 onthe valve shank with the Slot 27 the sleeve 2i), the latter is rotatedby the turning of knob 2d and is gradually moved axially through 4itsthreaded engagement with the interior of rod 8. The degree of opening ofthe valve is thus modied according to requirements.

Should a succession of comparatively large y,surface areas to be coatedbe interrupted by narrow surfaces too restricted in area to be properlycoated by a fan pattern the knob 26 is pushed forwardly sliding thevalve to its seat with the head of screw 23 travelling lengthwise ofthe-slot 27.

'When the work for the narrow spray pattern is completed the knob 26 ispulled rearwardly until the head of the screw 28 reaches the rear end ofthe slot 27. As this doesnt disturb the rotary position of the sleeve,the fan pattern previously selected for the regular run of surfaces isthus again produced.

The length of the threads between the sleeve 20 and the interior of rod8 is such that the valve may be rrnly held to its seat for a long spellof coating of surfaces of limited dimensions by turning the valve andcoacting sleeve until the valve reaches its seat.

From the preceding it may be understood that the slot and screwengagement between the valve shank and sleeve in association with thethreaded mounting of the sleeve provides means for both gradualadjustment of the valve position and rapid closing and reopening slidingmovement of the valve.

While a slot and screw engagement between the valve shank and thesurrounding sleeve is utilized in the preferred embodiment, it isrealized that there are analogous structures which would serve as well.For instance a groove of suieient depth would function as effectively asthe slot. Then teo, a pin or flattened tongue could be feasiblysubstituted for the screw. It is not considered that such replacementswould depart from the spirit of the invention and that slot and screw asherein specified should accordingly be interpreted broadly.

Also, it may be well to point out that it is not essential that the slotbe in the sleeve and the pin or screw be in the valve shank as thereverse positioning would work as well. In addition, it may be observedthat the valve shank could have a threaded engagement with the sleeveand the latter a slot and screw engagement with the rod without any lossin functions over the preferred form. For this reason the scope of thisinvention is not considered limited to a particular location of suchengaging structures.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

In a spray gun air valve, a unitary valve casing with Cal an air passagetherethrough, said passage having a lateral entering port and an axialdischarge port, a valve seat within the passage between the two ports, avalve for axial adjustment toward and away from said seat, a valveshank, a rotatable sleeve threadedly engaged within the casing andencompassing said shank, a pin and longitudinal slot connection betweenthe sleeve and shank within the valve casing, the pin of said connectionextending radially from the valve shank and the longitudinal slot ofsaid connection located in the wall of the sleeve and cutting throughthe portion of the sleeve which is externally threaded for engagementwithin the casing, a single manipulable head on the outer end of saidshank by a manual push or pull of which the valve is moved axiallywithin the limits permitted by the pin and slot connection toward oraway from the valve seat, and by a manual turning of which the sleeve isrotated upon its threaded engagement within the casing through the pinand slot connection between the sleeve and the shank, means locatedintermediate the manipulable head and the pin and slot connection forfrictionally retaining the valve in any selected position relative tothe sleeve, and means for frictionally retaining the sleeve in anyselected position relative to the casing.

References Cited in the ile of this patent UNITED STATES PATENTS 526,176Blair Sept. 18, 1894 733,532 Bailey July 14, 1903 1,379,389 BrassingtonMay 24, 1921 1,710,488 Oliphant Apr. 23, 1929 2,511,626 Einbecker Jan.13, 1950 2,514,025 Bush July 4, 1950 2,559,407 Dalrymple July 3, 19512,626,122 Lammirnan Jan. 20, 1953 FOREIGN PATENTS 8,318 Great Britain1894

